<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@page isELIgnored="false" %>
<html>
<body>
<h2>Hello World!</h2>
<form action="index.jsp" method="get">
    <input name="userName" type="text" value="${param.userName}">
    <input type="submit" value="登录">
</form>

<c:if test="${param.userName=='admin'}" var="isAdmin">
    <c:out value="你好！"/>
</c:if>

</body>
</html>
